poj3278(bfs)

poj3278(bfs)

http://poj.org/problem?id=3278


额额，bfs嘛，这个数据有点强哈，边界条件要搞清楚才能过呢。。呵呵，不错，bfs:

#include<stdio.h>
#include<string.h>
#include<math.h>
int n,k,ans,vis[100005],que[100005];

int bfs()
{
    int head,tail,now;

    memset(vis,0,sizeof(vis));

    head=0;
    tail=1;
    que[1]=n;
    vis[n]=1;

    while (head<tail)
    {
        head++;
        now=que[head];
        if (now<100000&&!vis[now+1])
        {
            if (now+1==k)
                return vis[now];
            tail++;
            que[tail]=now+1;
            vis[now+1]=vis[now]+1;
        }
        if (now>=1&&!vis[now-1])
        {
            if (now-1==k)
                return vis[now];
            tail++;
            que[tail]=now-1;
            vis[now-1]=vis[now]+1;
        }
        if (now>=1&&2*now<=100000&&!vis[2*now])
        {
            if (2*now==k)
                return vis[now];
            tail++;
            que[tail]=2*now;
            vis[2*now]=vis[now]+1;
        }
    }
}

int main()
{
    while (scanf("%d%d",&n,&k)==2)
    {
        if (k<=n)
            ans=n-k;
        else
            ans=bfs();
        printf("%d\n",ans);
    }
    return 0;
}

写代码要严谨才行啊，那些变量名什么一定要搞清楚呢！！！
这里就哉了的。